The use of the slip-form concept in construction machines for laying roads, curbs, etc. has been well known for many years. Such machines, however, are beset with one or more of the following shortcomings: (a) they are normally side loaded from trucks which travel along a path disposed to one side of and parallel with the base surface on which the concrete is to be laid and not from trucks moving ahead of the machine along the base surface over which the machine also subsequently passes; (b) they are difficult to maneuver along a prescribed path on the base surface; (c) because of the machine design, it is difficult and awkward to lay reinforcing mesh or rods ahead of the mule; (d) the machines were incapable of readily laying concrete where the contour of the base surface was of a semi-circular or concave configuration; (e) the machines are incapable of being used in tunnel construction or the like; (f) the machines are costly to maintain and service; (g) they require an inordinate number of operating personnel; and (h) the maximum width of the concrete to be laid at one time by the machine was substantially limited to the transverse spacing between the tracks of the machine.